Sex hormone suppression reduces resting energy expenditure and {beta}-adrenergic support of resting energy expenditure

Effect of Menstrual Cycle Phase and Hormonal Contraceptives on Resting Metabolic Rate and Body Composition

The cyclical changes in sex hormones across the menstrual cycle (MC) are associated with various biological changes that may alter resting metabolic rate (RMR) and body composition estimates. Hormonal contraceptive (HC) use must also be considered given their impact on endogenous sex hormone concentrations and synchronous exogenous profiles. The purpose of this study was to determine if RMR and dual-energy X-ray absorptiometry body composition estimates change across the MC and differ compared with HC users. This was accomplished during a 5-week training camp involving naturally cycling athletes (n = 11) and HC users (n = 7 subdermal progestin implant, n = 4 combined monophasic oral contraceptive pill, n = 1 injection) from the National Rugby League Indigenous Women's Academy. MC phase was retrospectively confirmed via serum estradiol and progesterone concentrations and a positive ovulation test. HC users had serum estradiol and progesterone concentrations assessed at the time point of testing. Results were analyzed using general linear mixed model. There was no effect of MC phase on absolute RMR (p = .877), relative RMR (p = .957), or dual-energy X-ray absorptiometry body composition estimates (p > .05). There was no effect of HC use on absolute RMR (p = .069), relative RMR (p = .679), or fat mass estimates (p = .766), but HC users had a greater fat-free mass and lean body mass than naturally cycling athletes (p = .028). Our findings suggest that RMR and dual-energy X-ray absorptiometry body composition estimates do not significantly differ due to changes in sex hormones in a group of athletes, and measurements can be compared between MC phases or with HC usage without variations in sex hormones causing additional noise.

Combined supplementation with hesperidin, phytosterols and curcumin decreases adiposity and improves metabolic health in ovariectomized rats

In recent years many women have looked for alternative therapies to address menopause. Hesperidin, phytosterols and curcumin are bioactive compounds that can ameliorate some cardiovascular risk factors associated with menopause, although there are no data concerning the effects of their combined supplementation. We used ovariectomized (OVX) rats, a postmenopausal model with oestrogen deficiency, to evaluate whether supplementation with a multi-ingredient (MI) including hesperidin, phytosterols and curcumin for 57 days would display beneficial effects against fat mass accretion and metabolic disturbances associated with menopause. Twenty OVX rats were orally supplemented with either MI (OVX-MI) or vehicle (OVX). Furthermore, 10 OVX rats orally received the vehicle along with subcutaneous injections of 17β-oestradiol biweekly (OVX-E2), whereas 10 rats were sham operated and received oral and injected vehicles (control group; SH). MI supplementation partly counteracted the fat mass accretion observed in OVX animals, which was evidenced by decreased total fat mass, adiposity index, the weight of retroperitoneal, inguinal and mesenteric white adipose tissue (MWAT) depots and MWAT adipocyte hypertrophy. These effects were accompanied by a significant decrease in the circulating levels of leptin and the mRNA levels of the fatty acid uptake-related genes Lpl and Cd36 in MWAT. These results were very similar to those observed in OVX-E2 animals. OVX-MI rats also displayed a higher lean body mass, lean/fat mass ratio, adiponectin-to-leptin ratio and insulin sensitivity than their OVX counterparts. Our findings can pave the way for using this MI formulation as an alternative therapy to manage obesity and to improve the cardiometabolic health of menopausal women.

Brown adipose tissue metabolism in women is dependent on ovarian status

In rodents, loss of estradiol (E2) reduces brown adipose tissue (BAT) metabolic activity. Whether E2 impacts BAT activity in women is not known. BAT oxidative metabolism was measured in premenopausal (n = 27; 35 ± 9 yr; body mass index = 26.0 ± 5.3 kg/m2) and postmenopausal (n = 25; 51 ± 8 yr; body mass index = 28.0 ± 5.0 kg/m2) women at room temperature and during acute cold exposure using [11C]acetate with positron emission tomography coupled with computed tomograph. BAT glucose uptake was also measured during acute cold exposure using 2-deoxy-2-[18F]fluoro-d-glucose. To isolate the effects of ovarian hormones from biological aging, measurements were repeated in a subset of premenopausal women (n = 8; 40 ± 4 yr; BMI = 28.0 ± 7.2 kg/m2) after 6 mo of gonadotropin-releasing hormone agonist therapy to suppress ovarian hormones. At room temperature, there was no difference in BAT oxidative metabolism between premenopausal (0.56 ± 0.31 min-1) and postmenopausal women (0.63 ± 0.28 min-1). During cold exposure, BAT oxidative metabolism (1.28 ± 0.85 vs. 0.91 ± 0.63 min-1, P = 0.03) and net BAT glucose uptake (84.4 ± 82.5 vs. 29.7 ± 31.4 nmol·g-1·min-1, P < 0.01) were higher in premenopausal than postmenopausal women. In premenopausal women who underwent gonadotropin-releasing hormone agonist, cold-stimulated BAT oxidative metabolism was reduced to a similar level (from 1.36 ± 0.66 min-1 to 0.91 ± 0.41 min-1) to that observed in postmenopausal women (0.91 ± 0.63 min-1). These results provide the first evidence in humans that reproductive hormones are associated with BAT oxidative metabolism and suggest that BAT may be a target to attenuate age-related reduction in energy expenditure and maintain metabolic health in postmenopausal women.NEW & NOTEWORTHY In rodents, loss of estrogen reduces brown adipose tissue (BAT) activity. Whether this is true in humans is not known. We found that BAT oxidative metabolism and glucose uptake were lower in postmenopausal compared to premenopausal women. In premenopausal women who underwent ovarian suppression to reduce circulating estrogen, BAT oxidative metabolism was reduced to postmenopausal levels. Thus the loss of ovarian function in women leads to a reduction in BAT metabolic activity independent of age.

Resting energy metabolism and sweet taste preference during the menstrual cycle in healthy women

Differences in blood concentration of sex hormones in the follicular (FP) and luteal (LP) phases may influence energy metabolism in women. We compared fasting energy metabolism and sweet taste preference on a representative day of the FP and LP in twenty healthy women (25·3 (sd 5·1) years, BMI: 22·2 (sd 2·2) kg/m2) with regular self-reported menses and without the use of hormonal contraceptives. From the self-reported duration of the three prior menstrual cycles, the predicted FP and LP visits were scheduled for days 5-12 and 20-25 after menses, respectively. The order of the FP and LP visits was randomly assigned. On each visit, RMR and RQ by indirect calorimetry, sweet taste preference by the Monell two-series forced-choice tracking procedure, serum fibroblast growth factor 21 by a commercial ELISA (FGF21, a liver-derived protein with action in energy balance, fuel oxidation and sugar preference) and dietary food intake by a 24-h dietary recall were determined. Serum progesterone and oestradiol concentrations displayed the expected differences between phases. RMR was lower in the FP v. LP (5042 (sd 460) v. 5197 (sd 490) kJ/d, respectively; P = 0·04; Cohen effect size, d rm = 0·33), while RQ showed borderline significant higher values (0·84 (sd 0·05) v. 0·81 (sd 0·05), respectively; P = 0·07; d rm = 0·62). Also, in the FP v. LP, sweet taste preference was lower (12 (sd 8) v. 16 (sd 9) %; P = 0·04; d rm = 0·47) concomitant with higher serum FGF21 concentration (294 (sd 164) v. 197 (sd 104) pg/ml; P < 0·01; d rm = 0·66). The menstrual cycle is associated with changes in energy expenditure, sweet taste preference and oxidative fuel partitioning.

Prefrontal cortex melanocortin 4 receptors (MC4R) mediate food intake behavior in male mice

BACKGROUND

Melanocortin 4 receptor (MC4R) activity in the hypothalamus is crucial for regulation of metabolism and food intake. The peptide ligands for the MC4R are associated with feeding, energy expenditure, and also with complex behaviors that orchestrate energy intake and expenditure, but the downstream neuroanatomical and neurochemical targets associated with these behaviors are elusive. In addition to strong expression in the hypothalamus, the MC4R is highly expressed in the medial prefrontal cortex, a region involved in executive function and decision-making.

METHODS

Using viral techniques in genetically modified male mice combined with molecular techniques, we identify and define the effects on feeding behavior of a novel population of MC4R expressing neurons in the infralimbic (IL) region of the cortex.

RESULTS

Here, we describe a novel population of MC4R-expressing neurons in the IL of the mouse prefrontal cortex that are glutamatergic, receive input from melanocortinergic neurons, and project to multiple regions that coordinate appetitive responses to food-related stimuli. The neurons are stimulated by application of MC4R-specific peptidergic agonist, THIQ. Deletion of MC4R from the IL neurons causes increased food intake and body weight gain and impaired executive function in simple food-related behavior tasks.

CONCLUSION

Together, these data suggest that MC4R neurons of the IL play a critical role in the regulation of food intake in male mice.

The Influence of Energy Balance and Availability on Resting Metabolic Rate: Implications for Assessment and Future Research Directions

Resting metabolic rate (RMR) is a significant contributor to an individual's total energy expenditure. As such, RMR plays an important role in body weight regulation across populations ranging from inactive individuals to athletes. In addition, RMR may also be used to screen for low energy availability and energy deficiency in athletes, and thus may be useful in identifying individuals at risk for the deleterious consequences of chronic energy deficiency. Given its importance in both clinical and research settings within the fields of exercise physiology, dietetics, and sports medicine, the valid assessment of RMR is critical. However, factors including varying states of energy balance (both short- and long-term energy deficit or surplus), energy availability, and prior food intake or exercise may influence resulting RMR measures, potentially introducing error into observed values. The purpose of this review is to summarize the relationships between short- and long-term changes in energetic status and resulting RMR measures, consider these findings in the context of relevant recommendations for RMR assessment, and provide suggestions for future research.

Sleep Fragmentation and Estradiol Suppression Decrease Fat Oxidation in Premenopausal Women

CONTEXT

Body fat gain associated with menopause has been attributed to estradiol (E2) withdrawal. Hypoestrogenism is unlikely to be the only contributing factor, however.

OBJECTIVE

Given the links between sleep and metabolic health, we examined the effects of an experimental menopausal model of sleep fragmentation on energy metabolism.

METHODS

Twenty premenopausal women (age 21-45 years) underwent a 5-night inpatient study during the mid-to-late follicular phase (estrogenized; n = 20) and the same protocol was repeated in a subset of the participants (n = 9) following leuprolide-induced E2 suppression (hypo-estrogenized). During each 5-night study, there were 2 nights of unfragmented sleep followed by 3 nights of fragmented sleep. Indirect calorimetry was used to assess fasted resting energy expenditure (REE) and substrate oxidation.

RESULTS

Sleep fragmentation in the estrogenized state increased the respiratory exchange ratio (RER) and carbohydrate oxidation while decreasing fat oxidation (all P < 0.01). Similarly, in the hypo-estrogenized state without sleep fragmentation, RER and carbohydrate oxidation increased and fat oxidation decreased (all P < 0.01); addition of sleep fragmentation to the hypo-estrogenized state did not produce further effects beyond that observed for either intervention alone (P < 0.05). There were no effects of either sleep fragmentation or E2 state on REE.

CONCLUSION

Sleep fragmentation and hypoestrogenism each independently alter fasting substrate oxidation in a manner that may contribute to body fat gain. These findings are important for understanding mechanisms underlying propensity to body fat gain in women across the menopause transition.

Obese Women Have a High Carbohydrate Intake without Changes in the Resting Metabolic Rate in the Luteal Phase

Hormonal changes are caused by the menstrual cycle phases, which influence resting metabolic rate and eating behavior. The aim of the study was to determine resting metabolic rate (RMR) and its association with dietary intake according to the menstrual cycle phase in lean and obese Chilean women. This cross-sectional analytical study included 30 adult women (15 lean and 15 with obesity). Body composition was measured with a tetrapolar bioelectrical impedance meter. Nutritional status was determined by adiposity. A 24-h recall of three nonconsecutive days verifies dietary intake. The RMR was measured by indirect calorimetry. All measurements were performed in both the follicular and luteal phases of the menstrual cycle. Statistical analyses were performed with STATA software at a significance level, which was α = 0.05. The RMR (β = 121.6 kcal/d), temperature (β = 0.36 °C), calorie intake (β = 317.1 kcal/d), and intake of lipids (β = 13.8 g/d) were associated with the luteal phase in lean women. Only extracellular water (β = 1.11%) and carbohydrate consumption (β = 45.2 g/d) were associated in women with obesity. Lean women showed increased RMR, caloric intake, and lipid intake during the luteal phase. For women with obesity, carbohydrate intake increased but not RMR.

Body composition and cardiometabolic health across the menopause transition

Every year, 2 million women reach menopause in the United States, and they may spend 40% or more of their life in a postmenopausal state. In the years immediately preceding menopause-known as the menopause transition (or perimenopause)-changes in hormones and body composition increase a woman's overall cardiometabolic risk. In this narrative review, we summarize the changes in weight, body composition, and body fat distribution, as well as the changes in energy intake, energy expenditure, and other cardiometabolic risk factors (lipid profile, glucose metabolism, sleep health, and vascular function), that occur during the menopause transition. We also discuss the benefits of lifestyle interventions in women in the earlier stages of menopause before these detrimental changes occur. Finally, we discuss how to include perimenopausal women in research studies so that women across the life-span are adequately represented.

Effect of oral contraceptives on energy balance in women: A review of current knowledge and potential cellular mechanisms

Body weight management is currently of major concern as the obesity epidemic is still a worldwide challenge. As women face more difficulties to lose weight than men, there is an urgent need to better understand the underlying reasons and mechanisms. Recent data have suggested that the use of oral contraceptive (OC) could be involved. The necessity of utilization and development of contraceptive strategies for birth regulation is undeniable and contraceptive pills appear as a quite easy approach. Moreover, OC also represent a strategy for the management of premenstrual symptoms, acne or bulimia nervosa. The exact impact of OC on body weight remains not clearly established. Thus, after exploring the potential underlying mechanisms by which OC could influence the two side of energy balance, we then provide an overview of the available evidence regarding the effects of OC on energy balance (i.e. energy expenditure and energy intake). Finally, we highlight the necessity for future research to clarify the cellular effects of OC and how the individualization of OC prescriptions can improve long-term weight loss management.

Active Women Across the Lifespan: Nutritional Ingredients to Support Health and Wellness

Women are the largest consumers of dietary supplements. Dietary supplements can play a role in health and performance, particularly for women. Growing evidence and innovations support the unique physiological and nutrient timing needs for women. Despite the need for more nutrition and exercise-specific research in women, initial data and known physiological differences between sexes related to the brain, respiration, bone, and muscle support new product development and evidence-based education for active women regarding the use of dietary supplements. In this narrative review, we discuss hormonal and metabolic considerations with the potential to impact nutritional recommendations for active women. We propose four potential areas of opportunity for ingredients to help support the health and well-being of active women, including: (1) body composition, (2) energy/fatigue, (3) mental health, and (4) physical health.

Dietary Intake and Energy Expenditure in Breast Cancer Survivors: A Review

Many breast cancer survivors (BCS) gain fat mass and lose fat-free mass during treatment (chemotherapy, radiation, surgery) and estrogen suppression therapy, which increases the risk of developing comorbidities. Whether these body composition alterations are a result of changes in dietary intake, energy expenditure, or both is unclear. Thus, we reviewed studies that have measured components of energy balance in BCS who have completed treatment. Longitudinal studies suggest that BCS reduce self-reported energy intake and increase fruit and vegetable consumption. Although some evidence suggests that resting metabolic rate is higher in BCS than in age-matched controls, no study has measured total daily energy expenditure (TDEE) in this population. Whether physical activity levels are altered in BCS is unclear, but evidence suggests that light-intensity physical activity is lower in BCS compared to age-matched controls. We also discuss the mechanisms through which estrogen suppression may impact energy balance and develop a theoretical framework of dietary intake and TDEE interactions in BCS. Preclinical and human experimental studies indicate that estrogen suppression likely elicits increased energy intake and decreased TDEE, although this has not been systematically investigated in BCS specifically. Estrogen suppression may modulate energy balance via alterations in appetite, fat-free mass, resting metabolic rate, and physical activity. There are several potential areas for future mechanistic energetic research in BCS (e.g., characterizing predictors of intervention response, appetite, dynamic changes in energy balance, and differences in cancer sub-types) that would ultimately support the development of more targeted and personalized behavioral interventions.

The Most Undertreated Chronic Disease: Addressing Obesity in Primary Care Settings

PURPOSE OF REVIEW

While obesity-related comorbidities are frequently addressed and treated in primary care (PC), obesity itself is undertreated. We review the current treatments for obesity and provide potential provider and system-level strategies for integrating weight management and improving longer term obesity care within PC settings.

RECENT FINDINGS

We now understand that the body develops multiple mechanisms to resist weight loss and promote weight regain, making both weight loss and weight loss maintenance challenging. Therefore, weight management often requires medically supervised interventions and should be treated on a long-term basis. However, there are multiple barriers to improving obesity care within PC settings. Clinically, utilizing strategies such as a shared decision-making approach and the 5As to discuss treatment options can facilitate formulating an obesity treatment plan. Utilizing telehealth, a team-based approach, and community partnering can increase patient access to intensive behavioral interventions. Future studies should evaluate other cost-effective methods to implement obesity care into the PC setting.

Novel Equations to Estimate Resting Energy Expenditure during Sitting and Sleeping

INTRODUCTION

Young and early middle-aged office workers spend most of the day sitting or sleeping. Few studies have used a metabolic chamber to report sitting resting energy expenditure (REE) or sleeping metabolic rate (SMR) estimation equations. This study aimed to develop novel equations for estimating sitting REE and SMR, and previously published equations for SMR were compared against measured values.

METHODS

The relationships among sitting REE, SMR, and body composition measured in clinical trials were analyzed. The body composition (fat-free mass [FFM] and fat mass) and energy metabolism of 85 healthy young and early middle-aged Japanese individuals were measured using dual-energy X-ray absorptiometry and a metabolic chamber, respectively. Novel estimate equations were developed using stepwise multiple regression analysis. Estimates of SMR using a new equation and 2 published equations were compared against measured SMR.

RESULTS

The sitting mREE and mSMR were highly correlated (r = 0.756, p < 0.01). The new FFM-based estimate accounted for 50.4% of the variance in measured sitting REE (mREE) and 82.3% of the variance in measured SMR (mSMR). The new body weight-based estimate accounted for 49.3% of the variance in sitting mREE and 82.2% of the variance in mSMR. Compared with mSMR, the SMR estimate using an FFM-based published equation was slightly underestimated.

CONCLUSION

These novel body weight- and FFM-based equations may help estimate sitting REE and SMR in young and early middle-aged adults. Previous SMR estimated FFM-based equations were slightly underestimated against measured SMR; however, we confirmed the previous SMR estimate equations could be useful. This finding suggests that sitting REE and SMR can be easily estimated from individual characteristics and applied in clinical settings.

A Randomized Controlled Trial of Ovarian Suppression in Premenopausal Women: No Change in Free-Living Energy Expenditure

OBJECTIVE

The purpose of this study was to determine whether suppression of ovarian function (gonadotropin-releasing hormone agonist [GnRH_AG ]) for 24 weeks in premenopausal women approaching menopause causes changes in body composition and a decline in free-living physical activity energy expenditure (PAEE) and whether endurance exercise training attenuates the changes.

METHODS

Premenopausal women who were approaching menopause (mean [SD]: age 46 [3] years, BMI 26.3 [4.8] kg/m² ) were randomized to 24 weeks of GnRH_AG (n = 14), GnRH_AG + Exercise (n = 11), or placebo (n = 9). Endurance exercise was performed 4 days per week with the goal of expending 200 to 300 kcal per session. Primary outcome measurements included body composition by dual-energy x-ray absorptiometry, total daily energy expenditure (TDEE), and PAEE by doubly labeled water, and resting energy expenditure (REE) by indirect calorimetry.

RESULTS

Changes in TDEE, PAEE, REE, or body composition were not different between groups. However, within the GnRH_AG group, fat mass increased (mean [SE]: total 1.7 [0.4] kg, trunk 0.9 [0.2] kg, leg 0.6 [0.2] kg) and fat-free leg mass decreased (mean [SE]: -0.4 [0.2] kg) significantly.

CONCLUSIONS

In premenopausal women approaching menopause, ovarian hormone suppression resulted in increased adiposity without alterations in TDEE, PAEE, or REE.

Estrogen and gut satiety hormones in vagus-hindbrain axis

Estrogens modulate different physiological functions, including reproduction, inflammation, bone formation, energy expenditure, and food intake. In this review, we highlight the effect of estrogens on food intake regulation and the latest literature on intracellular estrogen signaling. In addition, gut satiety hormones, such as cholecystokinin, glucagon-like peptide 1 and leptin are essential to regulate ingestive behaviors in the postprandial period. These peripheral signals are sensed by vagal afferent terminals in the gut wall and transmitted to the hindbrain axis. Here we 1. review the role of the vagus-hindbrain axis in response to gut satiety signals and 2. consider the potential synergistic effects of estrogens on gut satiety signals at the level of vagal afferent neurons and nuclei located in the hindbrain. Understanding the action of estrogens in gut-brain axis provides a potential strategy to develop estrogen-based therapies for metabolic diseases and emphasizes the importance of sex difference in the treatment of obesity.

Effect of menstrual cycle on resting metabolism: A systematic review and meta-analysis

Background

The need to control for the potential influence of menstrual cycle phase on resting metabolism (RMR) places a burden on research participants who must self-report onset of menstruation and researchers who must schedule metabolic testing accordingly.

Purpose

To systematically review and analyze existing research to determine the effect of menstrual cycle on RMR.

Methods

We searched PubMed, CINAHL, MEDLINE, SPORTDiscus, and Scopus databases using the search terms “menstrual cycle and metabolic rate” and “menstrual cycle and energy expenditure.” Eligibility criteria were English language, single-group repeated measures design, and RMR as either a primary or secondary outcome. Risk of bias was assessed based on study sample, measurement, and control of confounders. Differences between the follicular and luteal phases of the menstrual cycle were analyzed using the standardized mean difference in effect size.

Results

Thirty English-language studies published between 1930 and December 2019 were included in the systematic review, and 26 studies involving 318 women were included in the meta-analysis. Overall, there was a small but significant effect favoring increased RMR in the luteal phase (ES = 0.33; 95% CI = 0.17, 0.49, p < 0.001).

Discussion

Limitations include risk of bias regarding measurement of both menstrual cycle and RMR. Sample sizes were small and studies did not report control of potential confounders. Sub-group analysis demonstrated that in more recent studies published since 2000, the effect of menstrual phase was reduced and not statistically significant (ES = 0.23; 95% CI = -0.00, 0.47; p = 0.055). Until larger and better designed studies are available, based on our current findings, researchers should be aware of the potential confounding influence of the menstrual cycle and control for it by testing consistently in one phase of the cycle when measuring RMR in pre-menopausal women.

Sex differences in response to short-term high fat diet in mice

BACKGROUND

Consumption of high-fat diet (HF) leads to hyperphagia and increased body weight in male rodents. Female rodents are relatively resistant to hyperphagia and weight gain in response to HF, in part via effects of estrogen that suppresses food intake and increases energy expenditure. However, sex differences in energy expenditure and activity levels with HF challenge have not been systemically described. We hypothesized that, in response to short-term HF feeding, female mice will have a higher energy expenditure and be more resistant to HF-induced hyperphagia than male mice.

METHODS

Six-week-old male and female C57BL/6 J mice were fed either low fat (LF, 10% fat) or moderate HF (45% fat) for 5 weeks, and energy expenditure, activity and meal pattern measured using comprehensive laboratory animal monitoring system (CLAMS).

RESULTS

After 5 weeks, HF-fed male mice had a significant increase in body weight and fat mass, compared with LF-fed male mice. HF-fed female had a significant increase in body weight compared with LF-fed female mice, but there was no significant difference in fat mass. HF-fed male mice had lower energy expenditure compared to HF-fed female mice, likely due in part to reduced physical activity in the light phase. HF-fed male mice also had increased energy intake in the dark phase compared to LF-fed male mice and a reduced response to exogenous cholecystokinin-induced inhibition of food intake. In contrast, there was no difference in energy intake between LF-fed and HF-fed female mice.

CONCLUSIONS

The data show that female mice are generally protected from short-term HF-induced alterations in energy balance, possibly by maintaining higher energy expenditure and an absence of hyperphagia. However, HF-feeding in male mice induced weight and fat mass gain and hyperphagia. These findings suggest that there is a sex difference in the response to short-term HF-feeding in terms of both energy expenditure and control of food intake.

Temperature regulation in women: Effects of the menstrual cycle

Core body temperature changes across the ovulatory menstrual cycle, such that it is 0.3°C to 0.7°C higher in the post-ovulatory luteal phase when progesterone is high compared with the pre-ovulatory follicular phase. This temperature difference, which is most evident during sleep or immediately upon waking before any activity, is used by women as a retrospective indicator of an ovulatory cycle. Here, we review both historical and current literature aimed at characterizing changes in core body temperature across the menstrual cycle, considering the assessment of the circadian rhythm of core body temperature and thermoregulatory responses to challenges, including heat and cold exposure, exercise, and fever. We discuss potential mechanisms for the thermogenic effect of progesterone and the temperature-lowering effect of estrogen, and discuss effects on body temperature of exogenous formulations of these hormones as contained in oral contraceptives. We review new wearable temperature sensors aimed at tracking daily temperature changes of women across multiple menstrual cycles and highlight the need for future research on the validity and reliability of these devices. Despite the change in core body temperature across the menstrual cycle being so well identified, there remain gaps in our current understanding, particularly about the underlying mechanisms and microcircuitry involved in the temperature changes.

Modern pharmacological treatment of obese patients

There are many angles to consider in drug treatment of obese patients. On the one hand, some specific weight loss drugs are available, on the other, several drugs are associated with unintentional weight changes. When treating an obese patient for any given disease, several physiological changes may influence the pharmacokinetic properties of the drugs required. Thus, increased body weight may influence the efficacy and safety of some drug treatments. Even more complicated is the situation after weight reduction surgery. Due to the various changes to the gastrointestinal tract induced by the different surgical techniques used, and the dynamic changes in body composition thereafter, drug dosing has to be constantly reconsidered. Whereas all of these issues are of clinical importance, none of them have been investigated in the necessary depth and broadness to ensure safe and efficacious drug treatment of the massively obese patient. Individual considerations have to be based on comorbidities, concomitant medication, and on specific drug properties, for example, lipophilicity, volume of distribution, and metabolism. In this article we summarize the data available on different aspects of drug treatment in the obese patient with the hope of improving patient care.

UCP2, SHBG, Leptin, and T3 Levels are Associated with Resting Energy Expenditure in Obese Women

OBJECTIVE

The aim of this study was to investigate the association of Sex Hormone Binding Globulin (SHBG) with leptin, Triidothyronine (T3), and Uncoupling Protein 2 (UCP2) in obese women with low and normal Resting Energy Expenditure (REE) and to determine the role of these factors in the regulation of REE in obese women.

METHOD

A total 49 subjects (25-50 years old) were selected. Anthropometric and body composition parameters and resting energy expenditure were measured. Fasting circulating leptin, T3, SHBG and UCP2 levels were measured. Subjects were divided into three groups: Group І (BMI>30 and low resting energy expenditure, 16 subjects), group II (BMI>30 and normal resting energy expenditure, 17 subjects), and group ІІІ (control group, 16 non-obese subjects).

RESULT

It was found that obese subjects who had higher SHBG and leptin levels were at risk for high levels of UCP2. A significant association was found between T3 and REE. Obese subjects with higher concentrations of UCP2 and SHBG had decreased resting energy expenditure. A significant association was observed between SHBG and leptin in group І (r=0.90, p<0.0001) and group ІІ (r=0.83, p<0.0001). Moreover, a significant association was found between T3 and SHBG in group І (r=-0.69, P=0.003).

CONCLUSION

Changes of the UCP2, leptin, and thyroid hormone (T3) levels may be related to SHBG levels. Thus, lower leptin and T3 levels may decrease SHBG in obese women. Therefore, lower SHBG, leptin, T3 and UCP2 levels may decrease the REE level in obese women.

Basal metabolic rate in Brazilian patients with type 2 diabetes: comparison between measured and estimated values

OBJECTIVES

The aims of this study are to investigate which of the seven selected predictive equation for estimating basal metabolic rate (BMR) is the best alternative to indirect calorimetry (IC) and to evaluate the dietary energy intake in patients with type 2 diabetes.

SUBJECTS AND METHODS

Twenty-one patients with type 2 diabetes participated in this diagnostic test study. Clinical and laboratorial variables were evaluated as well as body composition by absorptiometry dual X-ray emission (DXA) and BMR measured by IC and estimated by prediction equations. Dietary intake was evaluated by a quantitative food frequency questionnaire. Data were analyzed using Bland-Altman plots, paired t-tests, and Pearson's correlation coefficients.

RESULTS

Patients were 62 (48-70) years old, have had diabetes for 8 (2-36) yeas, and 52.4% were females. The mean body composition comprised a fat-free mass of 49.8 ± 9.4 kg and a fat mass of 28.3 ± 7.2 kg. The energy intake was 2134.3 ± 730.2 kcal/day and the BMR by IC was 1745 ± 315 kcal/day. There was a wide variation in the accuracy of BMR values predicted by equations when compared to IC BMR measurement. Harris-Benedict, Oxford, FAO/WHO/UNO equations produced the smallest differences to IC, with a general bias of < 8%. The FAO/WHO/UNO equation provided the best BMR prediction in comparison to measured BMR.

CONCLUSION

In patients with type 2 diabetes, the equation of the FAO/WHO/UNO was the one closest to the BMR values as measured by IC.

Influence of Estradiol Status on Physical Activity in Premenopausal Women

PURPOSE

This study aimed to determine the effects of 5 months of ovarian hormone suppression in premenopausal women on objectively measured physical activity (PA).

METHODS

Participants (age, 35 ± 8 yr; body mass index, 27 ± 6 kg·m) received monthly intramuscular injections of gonadotropin-releasing hormone agonist (GnRHAG) therapy, which suppresses pituitary gonadotropins and results in suppression of ovarian sex hormones. Women were randomized to receive concurrent transdermal E2 (GnRHAG + E2; n = 30) or placebo (GnRHAG + PL, n = 31). PA was assessed for 1 wk before and during each month of the 5-month intervention using a hip-worn accelerometer (Actical, Mini Mitter Co., Inc., Bend, OR). Estimates of time spent in sedentary, light, and moderate-to-vigorous PA (MVPA) were derived using a previously published equation. Subsets of participants in each group were also randomized to a supervised progressive resistance exercise training program.

RESULTS

Total MVPA tended toward being higher (P = 0.08) in the GnRHAG + E2 group at month 4. There were no significant effects of intervention or time in sedentary or light PA. In the subset of women who did not participate in structured exercise training for which Actical data were obtained (n = 16 in each group), total MVPA was higher at month 4 (P = 0.01).

CONCLUSIONS

PA levels seem to be maintained at a higher level in women undergoing pharmacological suppression of ovarian function with E2 add-back when compared with women treated with placebo. These data provide proof-of-concept data that E2 contributes to the regulation of PA in humans. However, given the exploratory nature of this study, future confirmatory investigations will be necessary.

Curing breast cancer and killing the heart: A novel model to explain elevated cardiovascular disease and mortality risk among women with early stage breast cancer

Due to advances in prevention, early detection and treatment, early breast cancer mortality has decreased by nearly 40% during the last four decades. Yet, the risk of cardiovascular disease (CVD) mortality is significantly elevated following a breast cancer diagnosis, and it is a leading cause of death in this population. This review will discuss the most recent evidence for risks, pathology, mechanisms, and prevention of CVD morbidity and mortality in women with breast cancer. This evidence will be synthesized into a new model 'the compounding risk and protection model.' This model proposes that the balance between risk factors (i.e., older age, pre-existing traditional CVD risk factors and shared biologic pathways for CVD and cancer such as inflammation, as well as treatment-related and lifestyle toxicity) and potential protection factors (i.e., lifelong non-smoking, regular physical activity, a healthy diet rich in fruits and vegetables, and management of body weight and stress, heart failure therapy) determine the individual risk of CVD morbidity and mortality after diagnosis of early breast cancer.

Modulation of Energy Expenditure by Estrogens and Exercise in Women

Reducing estrogen in women results in decreases in energy expenditure, but the mechanism(s) remain largely unknown. We postulate that the loss of estrogens in women is associated with increased accumulation of bone marrow-derived adipocytes in white adipose tissue, decreased activity of brown adipose tissue, and reduced levels of physical activity. Regular exercise may counteract the effects of estrogen deficiency.

Menopausal Hormone Therapy Is Associated With Reduced Total and Visceral Adiposity: The OsteoLaus Cohort

CONTEXT

After menopause, fat mass (FM) and visceral adipose tissue (VAT) increase and nonbone lean body mass (LBM) decreases. Whether menopausal hormone therapy (MHT) reverses these changes remains controversial.

OBJECTIVE

To assess the effect of MHT on FM, VAT, and LBM before and after its withdrawal and evaluate potential confounders.

DESIGN

Cross-sectional study.

SETTING

General community.

PATIENTS OR OTHER PARTICIPANTS

Women of the OsteoLaus cohort (50 to 80 years old) who underwent dual-energy X-ray absorptiometry (DXA) with body composition assessment. After we excluded women with estrogen-modifying medications, the 1053 participants were categorized into current users (CUs), past users (PUs), and never users (NUs) of MHT.

INTERVENTION

None.

MAIN OUTCOME MEASURES

VAT measured by DXA was the primary outcome. We assessed subtotal and android FM, LBM, muscle strength (hand grip), and confounding factors (caloric intake, physical activity, biomarkers).

RESULTS

The groups significantly differed in age, NU < CU < PU. Age-adjusted VAT was lower in CUs than NUs (P = 0.03). CUs exhibited lower age-adjusted body mass index (BMI) (-0.9 kg/m2) and a trend for lower FM (-1.3 kg). The 10-year gain of VAT (P < 0.01) and subtotal and android FM (P < 0.05) was prevented in CUs. No difference in LBM or hand grip was detected. No residual effect was detected for PUs, including for early MHT discontinuers. The confounding factors did not significantly differ between groups except for higher caloric intake in PUs compared with NUs.

CONCLUSIONS

MHT is associated with significantly decreased VAT, BMI, and android FM. No benefit is detected for LBM. The benefits are not preserved in PUs, suggesting caution when MHT is discontinued.

Prior weight loss exacerbates the biological drive to gain weight after the loss of ovarian function

Both the history of obesity and weight loss may change how menopause affects metabolic health. The purpose was to determine whether obesity and/or weight loss status alters energy balance (EB) and subsequent weight gain after the loss of ovarian function. Female lean and obese Wistar rats were randomized to 15% weight loss (WL) or ad libitum fed controls (CON). After the weight loss period, WL rats were kept in EB at the reduced weight for 8 weeks prior to ovariectomy (OVX). After OVX, all rats were allowed to eat ad libitum until weight plateaued. Energy intake (EI), spontaneous physical activity, and total energy expenditure (TEE) were measured with indirect calorimetry before OVX, immediately after OVX, and after weight plateau. Changes in energy intake (EI), TEE, and weight gain immediately after OVX were similar between lean and obese rats. However, obese rats gained more total weight and fat mass than lean rats over the full regain period. Post-OVX, EI increased more (P ≤ 0.03) in WL rats (58.9 ± 3.5 kcal/d) than CON rats (8.5 ± 5.2 kcal/d), and EI partially normalized (change from preOVX: 20.5 ± 4.2 vs. 1.5 ± 4.9 kcal/day) by the end of the study. As a result, WL rats gained weight (week 1:44 ± 20 vs. 7 ± 25 g) more rapidly (mean = 44 ± 20 vs. 7 ± 25 g/week; P < 0.001) than CON Prior obesity did not affect changes in EB or weight regain following OVX, whereas a history of weight loss prior to OVX augmented disruptions in EB after OVX, resulting in more rapid weight regain.

Role of Sex Hormones in the Control of Vegetative and Metabolic Functions of Middle-Aged Women

Aims: In women's life, menopause is characterized by significant physiological changes often associated with an increase in body mass and obesity-associated sicknesses. Numerous researches described interdependencies of estrogen deficiency, aging, and resting energy expenditure (REE) downfall in the obesity correlated with the menopause. The aim of this study was to determining whether healthy, obese menopausal women underwent HRT treatment, showed changes in their REE, autonomic asset, and assessment of oxidative stress in comparison with obese pre- and post-menopausal women.

Methodology: In this study, we measured the body composition, the REE, the oxidative stress, the diet assimilation, and the autonomic nervous system activity in three groups: pre-menopause women (n = 50), post-menopause women following hormone-replacement therapy (HRT; n = 50), and post-menopause women not following HRT (n = 50).

Results: In the group with HRT a significant increase of the sympathetic activity and REE was described. Finally this group showed a notable increment of oxidative stress compared with the others, and utilizing BIA instrument, the free fat mass was increased respect to the fat mass of obese women.

Conclusion: The study highlights the importance of the HRT-related physiological changes that influence body weight in menopause women. This results are important because have a practical implications for prevention and/or treatment of the obesity.

Ovarian hormones and obesity

BACKGROUND

Obesity is caused by an imbalance between energy intake, i.e. eating and energy expenditure (EE). Severe obesity is more prevalent in women than men worldwide, and obesity pathophysiology and the resultant obesity-related disease risks differ in women and men. The underlying mechanisms are largely unknown. Pre-clinical and clinical research indicate that ovarian hormones may play a major role.

OBJECTIVE AND RATIONALE

We systematically reviewed the clinical and pre-clinical literature on the effects of ovarian hormones on the physiology of adipose tissue (AT) and the regulation of AT mass by energy intake and EE.

SEARCH METHODS

Articles in English indexed in PubMed through January 2016 were searched using keywords related to: (i) reproductive hormones, (ii) weight regulation and (iii) central nervous system. We sought to identify emerging research foci with clinical translational potential rather than to provide a comprehensive review.

OUTCOMES

We find that estrogens play a leading role in the causes and consequences of female obesity. With respect to adiposity, estrogens synergize with AT genes to increase gluteofemoral subcutaneous AT mass and decrease central AT mass in reproductive-age women, which leads to protective cardiometabolic effects. Loss of estrogens after menopause, independent of aging, increases total AT mass and decreases lean body mass, so that there is little net effect on body weight. Menopause also partially reverses women's protective AT distribution. These effects can be counteracted by estrogen treatment. With respect to eating, increasing estrogen levels progressively decrease eating during the follicular and peri-ovulatory phases of the menstrual cycle. Progestin levels are associated with eating during the luteal phase, but there does not appear to be a causal relationship. Progestins may increase binge eating and eating stimulated by negative emotional states during the luteal phase. Pre-clinical research indicates that one mechanism for the pre-ovulatory decrease in eating is a central action of estrogens to increase the satiating potency of the gastrointestinal hormone cholecystokinin. Another mechanism involves a decrease in the preference for sweet foods during the follicular phase. Genetic defects in brain α-melanocycte-stimulating hormone-melanocortin receptor (melanocortin 4 receptor, MC4R) signaling lead to a syndrome of overeating and obesity that is particularly pronounced in women and in female animals. The syndrome appears around puberty in mice with genetic deletions of MC4R, suggesting a role of ovarian hormones. Emerging functional brain-imaging data indicates that fluctuations in ovarian hormones affect eating by influencing striatal dopaminergic processing of flavor hedonics and lateral prefrontal cortex processing of cognitive inhibitory controls of eating. There is a dearth of research on the neuroendocrine control of eating after menopause. There is also comparatively little research on the effects of ovarian hormones on EE, although changes in ovarian hormone levels during the menstrual cycle do affect resting EE.

WIDER IMPLICATIONS

The markedly greater obesity burden in women makes understanding the diverse effects of ovarian hormones on eating, EE and body adiposity urgent research challenges. A variety of research modalities can be used to investigate these effects in women, and most of the mechanisms reviewed are accessible in animal models. Therefore, human and translational research on the roles of ovarian hormones in women's obesity and its causes should be intensified to gain further mechanistic insights that may ultimately be translated into novel anti-obesity therapies and thereby improve women's health.

Role of Autonomic Nervous System and Orexinergic System on Adipose Tissue

Adipose tissue, defined as white adipose tissue (WAT) and brown adipose tissue (BAT), is a biological caloric reservoir; in response to over-nutrition it expands and, in response to energy deficit, it releases lipids. The WAT primarily stores energy as triglycerides, whereas BAT dissipates chemical energy as heat. In mammals, the BAT is a key site for heat production and an attractive target to promote weight loss. The autonomic nervous system (ANS) exerts a direct control at the cellular and molecular levels in adiposity. The sympathetic nervous system (SNS) provides a complex homeostatic control to specifically coordinate function and crosstalk of both fat pads, as indicated by the increase of the sympathetic outflow to BAT, in response to cold and high-fat diet, but also by the increase or decrease of the sympathetic outflow to selected WAT depots, in response to different lipolytic requirements of these two conditions. More recently, a role has been attributed to the parasympathetic nervous system (PNS) in modulating both adipose tissue insulin-mediated glucose uptake and fatty free acid (FFA) metabolism in an anabolic way and its endocrine function. The regulation of adipose tissue is unlikely to be limited to the autonomic control, since a number of signaling cytokines and neuropeptides play an important role, as well. In this review, we report some experimental evidences about the role played by both the ANS and orexins into different fat pads, related to food intake and energy expenditure, with a special emphasis on body weight status and fat mass (FM) content.

Reduction in energy expenditure during weight loss is higher than predicted based on fat free mass and fat mass in older adults

BACKGROUND & AIM

The aim of this study was to describe a decrease in resting energy expenditure during weight loss that is larger than expected based on changes in body composition, called adaptive thermogenesis (AT), in overweight and obese older adults.

METHODS

Multiple studies were combined to assess AT in younger and older subjects. Body composition and resting energy expenditure (REE) were measured before and after weight loss. Baseline values were used to predict fat free mass and fat mass adjusted REE after weight loss. AT was defined as the difference between predicted and measured REE after weight loss. The median age of 55 y was used as a cutoff to compare older with younger subjects. The relation between AT and age was investigated using linear regression analysis.

RESULTS

In this study 254 (M = 88, F = 166) overweight and obese subjects were included (BMI: 31.7 ± 4.4 kg/m², age: 51 ± 14 y). The AT was only significant for older subjects (64 ± 185 kcal/d, 95% CI [32, 96]), but not for younger subjects (19 ± 152 kcal/d, 95% CI [-9, 46]). The size of the AT was significantly higher for older compared to younger adults (β = 47, p = 0.048), independent of gender and type and duration of the weight loss program.

CONCLUSIONS

We conclude that adaptive thermogenesis is present only in older subjects, which might have implications for weight management in older adults. A reduced energy intake is advised to counteract the adaptive thermogenesis.

Core body temperature is lower in postmenopausal women than premenopausal women: potential implications for energy metabolism and midlife weight gain

OBJECTIVE

Weight gain during the menopausal transition is common. Although studies have suggested that weight gain is more likely related to aging than menopause, there is a reduction in resting energy expenditure with surgical or natural menopause which is independent of age and changes in body composition. The underlying mechanisms could include a reduction in core body temperature.

METHODS

Data were obtained from two related studies. Sample size was 23 men and 25 women (12 premenopausal,13 postmenopausal). In the Clinical Research Unit, core temperature was measured every minute for 24 hours (CorTemp System,HQ Inc.).

RESULTS

Mean 24-hour core body temperature was 0.25 ± 0.06 °C lower in postmenopausal than premenopausal women (p=0.001). Mean 24-hour core temperature was 0.34 ± 0.05 °C lower in men than in premenopausal women (p<0.001).

CONCLUSIONS

Postmenopausal women, like men, had lower core body temperatures than premenopausal women. This may have implications for midlife weight gain.

Low resting metabolic rate in exercise-associated amenorrhea is not due to a reduced proportion of highly active metabolic tissue compartments

Exercising women with menstrual disturbances frequently display a low resting metabolic rate (RMR) when RMR is expressed relative to body size or lean mass. However, normalizing RMR for body size or lean mass does not account for potential differences in the size of tissue compartments with varying metabolic activities. To explore whether the apparent RMR suppression in women with exercise-associated amenorrhea is a consequence of a lower proportion of highly active metabolic tissue compartments or the result of metabolic adaptations related to energy conservation at the tissue level, RMR and metabolic tissue compartments were compared among exercising women with amenorrhea (AMEN; n = 42) and exercising women with eumenorrheic, ovulatory menstrual cycles (OV; n = 37). RMR was measured using indirect calorimetry and predicted from the size of metabolic tissue compartments as measured by dual-energy X-ray absorptiometry (DEXA). Measured RMR was lower than DEXA-predicted RMR in AMEN (1,215 ± 31 vs. 1,327 ± 18 kcal/day, P < 0.001) but not in OV (1,284 ± 24 vs. 1,252 ± 17, P = 0.16), resulting in a lower ratio of measured to DEXA-predicted RMR in AMEN (91 ± 2%) vs. OV (103 ± 2%, P < 0.001). AMEN displayed proportionally more residual mass (P < 0.001) and less adipose tissue (P = 0.003) compared with OV. A lower ratio of measured to DXA-predicted RMR was associated with lower serum total triiodothyronine (ρ = 0.38, P < 0.001) and leptin (ρ = 0.32, P = 0.004). Our findings suggest that RMR suppression in this population is not the result of a reduced size of highly active metabolic tissue compartments but is due to metabolic and endocrine adaptations at the tissue level that are indicative of energy conservation.

The aging influence on cardiorespiratory, metabolic, and energy expenditure adaptations in head-out aquatic exercises: Differences between young and elderly women

The purpose of this study was to: (1) establish the relationship between acute physiological responses and musical cadence; and (2) compare physiologic responses between young and older women. Eighteen older (mean = 65.06 ± 5.77 years) and 19 young (mean = 22.16 ± 2.63 years) women underwent an intermittent and progressive protocol performing the head-out aquatic exercise the "rocking horse." Results showed that older women demonstrated lower mean heart rate, blood lactate concentration (bLa), and oxygen uptake (VO₂) at rest. Hierarchical linear modeling showed that variations in the rating of perceived effort and individual metabolic equivalent of task did not differ significantly by age group. However, during exercise, physiological responses of younger women were significantly different than for older women: in mean values, for each increased musical beat per minute, mean bLa was 0.003 mmol/l, VO₂ was 0.024 ml/kg/min, and energy expenditure was 0.0001 kcal/kg/min higher for younger women. This study shows that increases in musical cadence increased the cardiorespiratory, metabolic, and energy expenditure responses. However, these responses during increasing intensity seemed to differ between young and older women, with lower values for the elderly group, when performing head-out aquatic exercises.

The impact of short-term depot-medroxyprogesterone acetate treatment on resting metabolic rate

OBJECTIVE

This study examines the effect of a progestogen (depot-medroxyprogesterone acetate, DMPA) on resting metabolic rate (RMR) in a cohort of young, normal-weight healthy women. We hypothesize an increase in RMR and nonshivering thermogenesis (NST) resulting in increased body temperature by DMPA.

STUDY DESIGN

We performed a prospective cohort study in 13 subjects tested at baseline, 3 weeks and 9 weeks after 150 mg intramuscular DMPA administration. RMR was determined with indirect calorimetry. Secondary endpoints included changes in body mass index (BMI), body composition, temperature and serum levels of estradiol (E2), luteinizing hormone (LH), progesterone and MPA.

RESULTS

The percent change in RMR from baseline to week 3 (9%) was significantly higher than the percent change from baseline to week 9 (1.6%) (p=.045). The greatest percent change from baseline to week 3 compared to baseline to week 9 was seen in women initiating DMPA in the luteal phase of the cycle. Hypothalamic-pituitary-ovarian axis was evident by decreases in E2, LH and progesterone. DMPA resulted in increased body temperature with a significant correlation between the change in body temperature and the change in RMR. No change in body composition was seen.

CONCLUSIONS

RMR and NST increased in young healthy women with normal BMI 3 weeks after receiving the initial dose of 150 mg DMPA for contraception. The effect was augmented when the drug was administered during the luteal phase of the menstrual cycle.

IMPLICATION

DMPA increases RMR and thermogenesis independent of changes in body mass. An increase in weight with chronic DMPA may result from a combination of hyperphagia and abnormal NST in predisposed individuals.

Evaluation of a new whole room indirect calorimeter specific for measurement of resting metabolic rate

BACKGROUND

The most common methods for obtaining human resting metabolic rate (RMR) use either a ventilated hood connected to a metabolic cart (VH_MC) or calculation by many prediction equations utilizing the person's height and weight. These methods may be inherently inaccurate. The objective of this study is to compare the accuracy for the measurement of RMR by three methods: a new whole room indirect calorimeter specific for this purpose (RMR_WRIC), VH_MC and calculation by the Mifflin equation (ME). First, the VH_MC (Vmax Encore 2900, Carefusion Inc, San Diego, CA) and RMR_WRIC (Promethion GA-6/FG-1, Sable Systems Intl, Las Vegas, NV) were subjected to 10, one-hour ethanol (99.8 % purity) and propane (99.5 % purity) combustion tests, respectively, for simulated metabolic measurements. Thereafter, 40 healthy adults (22 M/18 F, 78.0 ± 24.5 kg, BMI = 25.6 ± 4.8, age 36.6 ± 13.4 years) had one-hour RMR (kcal), ventilation (liters) rates of oxygen (VO2), carbon dioxide (VCO2) and RQ (VCO2/VO2) measured after a 12-h fast with both the VH_ MC and the RMR_WRIC in a randomized fashion. The resting state was documented by heart rate. The RMR was also calculated using the ME, which was compared to both the RMR_WRIC and the VH_MC. All simulated and human metabolic data were extrapolated to 24-h and analyzed (SPSS, Ver. 22).

RESULTS

Comparing stoichiometry to actual combustion, the VH_MC underestimated simulated RMR (p < 0.05), VO2 (p < 0.05), VCO2 (p < 0.05) and the RQ. Similarly the RMR_WRIC underestimated simulated RMR (p < 0.05) and VO2 while overestimating VCO2 and the RQ. There was much greater variability in the simulated metabolic data between combustion and the VH_MC as compared to that of the RMR_WRIC. With regards to the volunteers, the RMR, RQ, VO2 and VCO2 determined by the VH_MC tended to be lower in comparison to these measurements determined by the RMR_WRIC. Finally, RMR calculated utilizing the ME was significantly (p < 0.05) less than the RMR_WRIC but similar to that obtained by the VH_MC.

CONCLUSION

The RMR_WRIC was more accurate and precise than either the VH_MC or ME, which has implications for determining energy requirements for individuals participating in weight loss or nutrition rehabilitation programs.

Regulation of energy expenditure by estradiol in premenopausal women

Suppressing sex hormones in women for 1 wk reduces resting energy expenditure (REE). The effects of more chronic suppression on REE and other components of total energy expenditure (TEE), and whether the reduction in REE is specifically due to loss of estradiol (E2), are not known. We compared the effects of 5 mo of sex hormone suppression (gonadotropin releasing hormone agonist therapy, GnRHAG) with placebo (PL) or E2 add-back therapy on REE and the components of TEE. Premenopausal women received GnRHAG (leuprolide acetate 3.75 mg/mo) and were randomized to receive transdermal therapy that was either E2 (0.075 mg/d; n = 24; means ± SD, aged = 37 ± 8 yr, BMI = 27.3 ± 6.2 kg/m(2)) or placebo (n = 21; aged = 34 ± 9 yr, BMI = 26.8 ± 6.2 kg/m(2)). REE was measured by using a metabolic cart, and TEE, sleep EE (SEE), exercise EE (ExEE, 2 × 30 min bench stepping), non-Ex EE (NExEE), and the thermic effect of feeding (TEF) were measured by using whole room indirect calorimetry. REE decreased in GnRHAG+PL [mean (95% CI), -54 (-98, -15) kcal/d], but not GnRHAG+E2 [+6 (-33, +45) kcal/d] (difference in between-group changes, P < 0.05). TEE decreased in GnRHAG+PL [-128 (-214, -41) kcal/d] and GnRHAG+E2 [-96 (-159, -32) kcal/d], with no significant difference in between-group changes (P = 0.55). SEE decreased similarly in both GnRHAG+PL [-0.07 (-0.12, -0.03) kcal/min] and GnRHAG+E2 [-0.07 (-0.12, -0.02) kcal/min]. ExEE decreased in GnRHAG+PL [-0.46 (-0.79, -0.13) kcal/min], but not GnRHAG+E2 [-0.30 (-0.65, +0.06) kcal/min]. There were no changes in TEF or NExEE in either group. In summary, chronic pharmacologic suppression of sex hormones reduced REE and this was prevented by E2 therapy.

Regulation of Body Composition and Bioenergetics by Estrogens

Evidence points to an important role of estradiol (E2) in the regulation of body composition and bioenergetics. Basic and preclinical research shows that the disruption of E2 signaling through either genetic manipulation or surgical intervention accelerates fat accumulation, with a disproportionate increase in abdominal fat. Clinical evidence for the regulation of body composition and bioenergetics by E2 is less consistent. Evidence exists both for and against menopause as the mediator of changes in body composition. Thus, a need remains to better understand the metabolic actions of estrogens in women and the potential impact on health after the menopause.

Effect of combined aerobic and resistance training in body composition of obese postmenopausal women

The aim of this study was to investigate the effects of a 16-week program of combined aerobic and resistance training on the body composition of postmenopausal women who are obese. The participants were divided into two groups: training group (TG, n = 37) and non-trained control group (CG, n = 18). The trunk fat, fat mass, percentage of fat mass and fat-free mass were estimated using DXA. Three nonconsecutive 24-hour dietary recalls were conducted. The training protocol consisted of 50 minutes of resistance training followed by 30 minutes of aerobic training. After the 16-week training program, differences were observed in trunk fat (CG= 0.064 x TG= -0.571 Kg; p-value = .020), fat mass (CG= -0.088 x TG= -1.037 Kg; p-value = .020) and fat-free mass (CG= -0.388 x TG= 1.049 Kg; p = .001). Therefore, a 16-week program of systematic combined aerobic and resistance training in obese postmenopausal women was effective in improving fat-free mass and decreasing both whole and abdominal adiposity.

Challenges and methodology for testing young healthy women in physiological studies

Physiological responses and control of body systems differ between women and men. Moreover, within women, female gonadal hormones have important influences on organs and systems outside of reproduction. Until the NIH Revitalization Act of 1993, laboratories focused physiological research primarily on men, and this focus placed limitations on women's health care. Thus, the NIH directive to include women required scientists and physicians studying humans to consider female reproductive physiology. Even though this directive was enacted over 20 years ago, there is still a great deal of misunderstanding as to the best methods to control hormones or account for changes in internal hormone exposure in women. This discussion describes common methods investigators use to include women in physiological studies and to examine the impact of female reproductive hormone exposure for research purposes. In some cases, the goal is to control for phase of the cycle, so women are studied when the endogenous hormones should be similar to each other. When the goal of the research is to examine the effects of hormones on a physiological response, it is important to use methods that will change hormone exposure in a controlled fashion. We recommend a method that employs gonadotropin-releasing hormone (GnRH) agonist or antagonist to suppress estrogens, gonadotropins, progesterone, and androgens followed by administration of these hormones. While this method is more invasive, it is safe and is the strongest research design to examine both hormone effects within women and between women and men.

Estrogen or raloxifene during postmenopausal weight loss: adiposity and cardiometabolic outcomes

OBJECTIVE

Estrogen-based hormone therapy (HT) attenuates abdominal fat gain after menopause, but whether HT improves abdominal fat loss during weight loss is unknown. It was hypothesized that HT or a selective estrogen receptor modulator (raloxifene) would augment reductions in abdominal visceral fat during weight loss when compared to placebo, potentially increasing improvements in glucose tolerance and lipid profile.

METHODS

Healthy postmenopausal women (n = 119; age 50-70 yr) underwent a 6-month weight-loss (primarily exercise) intervention with randomization to raloxifene (60 mg/d), HT (conjugated estrogens, 0.625 mg/d), or placebo. Outcomes were change in total and abdominal (visceral and subcutaneous) fat mass, lipid profile, and fasting and post-challenge glucose and insulin.

RESULTS

Neither HT nor raloxifene augmented loss of total or abdominal fat mass during exercise-induced weight loss when compared with placebo. Weight loss-induced improvements in risk factors were similar among the three groups, except for a greater reduction in fasted glucose in the HT group (difference in change [95%CI] from placebo; -0.40 [-0.76, -0.05]) and greater reductions in LDL (-0.36 [-0.63, -0.09]) and increases in HDL (0.15 [0.07, 0.24]) in both treatment groups.

CONCLUSIONS

Postmenopausal HT and raloxifene did not increase abdominal fat loss during weight loss, but did improve some cardiometabolic outcomes.

Discrepancy between exercise performance, body composition, and sex steroid response after a six-week detraining period in professional soccer players

Purpose

The aim of this study was to examine the effects of a six-week off-season detraining period on exercise performance, body composition, and on circulating sex steroid levels in soccer players.

Methods

Fifty-five professional male soccer players, members of two Greek Superleague Teams (Team A, n = 23; Team B, n = 22), participated in the study. The first two weeks of the detraining period the players abstained from any physical activity. The following four weeks, players performed low-intensity (50%–60% of VO₂max) aerobic running of 20 to 30 minutes duration three times per week. Exercise performance testing, anthropometry, and blood sampling were performed before and after the six-week experimental period.

Results

Our data showed that in both teams A and B the six-week detraining period resulted in significant reductions in maximal oxygen consumption (60,31±2,52 vs 57,67±2,54; p<0.001, and 60,47±4,13 vs 58,30±3,88; p<0.001 respectively), squat-jump (39,70±3,32 vs 37,30±3,08; p<0.001, and 41,05±3,34 vs 38,18±3,03; p<0.001 respectively), and countermovement-jump (41,04±3,99 vs 39,13±3,26; p<0.001 and 42,82±3,60 vs 40,09±2,79; p<0.001 respectively), and significant increases in 10-meters sprint (1,74±0,063 vs 1,79±0,064; p<0.001, and 1,73±0,065 vs 1,78±0,072; p<0.001 respectively), 20-meters sprint (3,02±0,05 vs 3,06±0,06; p<0.001, and 3,01±0,066 vs 3,06±0,063; p<0.001 respectively), body fat percentage (Team A; p<0.001, Team B; p<0.001), and body weight (Team A; p<0.001, Team B; p<0.001). Neither team displayed any significant changes in the resting concentrations of total-testosterone, free-testosterone, dehydroepiandrosterone-sulfate, Δ4-androstenedione, estradiol, luteinizing hormone, follicle-stimulating hormone, and prolactin. Furthermore, sex steroids levels did not correlate with exercise performance parameters.

Conclusion

Our results suggest that the six-week detraining period resulted in a rapid loss of exercise performance adaptations and optimal body composition status, but did not affect sex steroid resting levels. The insignificant changes in sex steroid concentration indicate that these hormones were a non-contributing parameter for the observed negative effects of detraining on exercise performance and body composition.

Comparison of predictive equations for resting energy expenditure among patients with schizophrenia in Japan

BACKGROUND

Recently, a relationship between obesity and schizophrenia has been reported. The prediction of resting energy expenditure (REE) is important to determine the energy expenditure of patients with schizophrenia. However, there is a lack of research concerning the most accurate REE predictive equations among Asian patients with schizophrenia. The purpose of the study reported here was to compare the validity of four REE equations for patients with schizophrenia taking antipsychotics.

METHODS

For this cross-sectional study, we recruited patients (n=110) who had a Diagnostic and Statistical Manual of Mental Disorders, fourth edition, diagnosis of schizophrenia and were admitted to four psychiatric hospitals. The mean (± standard deviation) age of these patients was 45.9±13.2 years. Anthropometric measurements (of height, weight, body mass index) were taken at the beginning of the study. REE was measured using indirect calorimetry. Comparisons between the measured and estimated REEs from the four equations (Harris-Benedict, Mifflin-St Jeor, Food and Agriculture Organization/World Health Organization/United Nations University, and Schofield) were performed using simple linear regression analysis and Bland-Altman analysis.

RESULTS

Significant trends were found between the measured and predicted REEs for all four equations (P<0.001), with the Harris-Benedict equation demonstrating the strongest correlation in both men and women (r=0.617, P<0.001). In all participants, Bland-Altman analysis revealed that the Harris-Benedict and Mifflin-St Jeor equations did not show a significant bias in the prediction of REE, however, a significant overestimation error was shown for the Food and Agriculture Organization/World Health Organization/United Nations University and Schofield equations.

CONCLUSION

When estimating REE in patients with schizophrenia taking antipsychotics, the Harris-Benedict equation appears to be the most appropriate for clinical use.

Moderate to high levels of exercise are associated with higher resting energy expenditure in community-dwelling postmenopausal women

Postmenopausal women experience an age-related decline in resting energy expenditure (REE), which is a risk factor for energy imbalance and metabolic disease. Exercise, because of its association with greater lean tissue mass and other factors, has the potential to mediate REE decline, but the relation between exercise and REE in postmenopausal women is not well characterized. This study tests the hypothesis that exercise energy expenditure (EEE) is positively associated with REE and can counter the effects of age and menopause. It involves a cross-sectional sample of 31 healthy postmenopausal women (aged 49-72 years) with habitual exercise volumes at or above levels consistent with current clinical recommendations. Subjects kept exercise diaries for 4 weeks that quantified exercise activity and were measured for body composition, maximal oxygen uptake, and REE. Multiple regression analysis was used to test for associations between EEE, age, body composition, and REE. There was a significant positive relation between EEE and lean tissue mass (fat-free mass and fat-free mass index). The relation between REE and EEE remained significant even after controlling for lean tissue mass. These results support the hypothesis that exercise is positively associated with REE and can counter the negative effects of age and menopause. They also indicate a continuous relation between exercise and REE across ranges of exercise, from moderate to high. Exercise at levels that are at or above current clinical guidelines might, in part, ameliorate the risk for energy imbalance and metabolic disease because of its positive relation with REE.

Activity of autonomic nervous system is related to body weight in pre-menopausal, but not in post-menopausal women

This study analyzed vegetative modulation, expressed as heart rate variability (HRV) power spectral analysis, in lean and obese women at pre-menopausal or post-menopausal age to reveal possible differences in menopause-related autonomic activity in lean and obese subjects. Sedentary women (n = 40) were divided in four groups: pre-menopausal lean and obese women, post-menopausal lean and obese subjects. The HRV-power spectrum was evaluated on a 5-min long ECG recording. The absolute values of the spectrum were summed in the following frequencies: a low-frequency (0.04-0.15 Hz; LF) and high-frequency (0.15-0.40; HF) range. LF and HF were values used to estimate the sympathetic and parasympathetic activity. LF and HF values of pre-menopausal obese women are lower than values of lean women. The menopause induced a same decrease in LF and HF values in lean and obese subjects, so that no difference was found in post-menopausal groups. This experiment indicates that modifications of autonomic modulation can be included among factors related to obesity in pre-menopausal, but not post-menopausal women.

Poor sleep quality and sleep apnea are associated with higher resting energy expenditure in obese individuals with short sleep duration

CONTEXT

Epidemiological studies reported an inverse or U-shaped relationship between sleep duration and weight. The relationship between sleep and resting energy expenditure (REE) has not been well characterized.

OBJECTIVE

The aim of the study was to determine the relationship between sleep, REE, and stress hormones.

DESIGN AND SETTING

We conducted a cross-sectional evaluation of a prospective cohort study at a tertiary referral research clinical center.

SUBJECTS

Subjects included 126 obese individuals (30 males, 96 females; age, 40.5 ± 6.9 yr; body mass index, 38.6 ± 6.5 kg/m(2); sleep duration, 360 ± 50 min/night; and sleep efficiency, 79.5 ± 7.5%).

MAIN OUTCOME MEASURE(S)

REE and respiratory quotient (RQ) were assessed by indirect calorimetry. Sleep duration and sleep efficiency were assessed by actigraphy. Sleep quality was estimated by questionnaires, and sleep apnea was evaluated by respiratory disturbance index (RDI). Morning plasma ACTH, serum cortisol, and 24-h urinary free cortisol and catecholamines were also measured.

RESULTS

RDI was positively correlated with REE adjusted by fat-free mass (r = 0.307; P = 0.003) and RQ (r = 0.377; P < 0.001). Sleep efficiency was inversely correlated with RQ (r = -0.200; P = 0.033). The relationship of RDI score and REE was stronger in men than women (P = 0.03). In women, serum cortisol was positively correlated (r = 0.407; P < 0.001), and Epworth sleepiness score tended to be inversely (r = -0.190; P = 0.086) correlated with adjusted REE. The RQ was positively related to RDI in women, whereas subjective sleep time was related to RQ in men. In a multiple regression model, RDI, serum cortisol, and urinary norepinephrine were directly related to REE, whereas serum cortisol also directly related to adjusted REE.

CONCLUSION

Poor sleep quality was associated with increased REE, a higher RQ indicating a shift from fat toward carbohydrate oxidation, and activation of the stress system.

Fat-free mass can be utilized to assess resting energy expenditure for male athletes of different body size

The fat-free mass (FFM) of athletes is typically large, and thus the FFM is often utilized to estimate their resting energy expenditure (REE). While the proportional contribution of organ-tissues to the total influence of FFM on REE is known for untrained individuals and female athletes, the extent to which this is valid for male athletes is unclear. The purpose of this study was to clarify the contribution of the components of FFM to REE in male athletes. Fifty-seven male athletes participated in this study. REE was assessed by indirect calorimetry and body composition by dual X-ray absorptiometry. The athletes were equally divided into three groups based on FFM: Small (S), Medium (M), and Large (L). When measured REE (REEm) was compared with REE estimated (REEe) based on the four organ-tissue compartments with set metabolic rates, REEm and REEe had a strong association (r=0.76, p<0.001). In addition, the absolute value of total REE became larger in accordance with body size (S: 1,643±144, M: 1,865±140, and L: 2,060±156 kcal/d) accompanied by increases in mass of all four organ-tissue compartments as body size increased. The consistency of REE/FFM in male athletes in spite of the difference in body size can be explained by the steadiness among the three groups of the relative contribution of each organ-tissue compartment to the FFM. Based on these results, the FFM is the major determinant of REE regardless of body size in male athletes.

Resposta da taxa metabólica de repouso após 16 semanas de treinamento com pesos em mulheres na pós-menopausa

INTRODUÇÃO: As alterações corporais provenientes da menopausa como a diminuição da massa magra (MM), aumento e redistribuição da gordura corporal e diminuição do gasto energético de repouso, colaboram para o aumento nas dimensões corporais e subsequente aumento da massa corporal total. Nesse sentido, os benefícios reconhecidos do treinamento com pesos (TP) não estão atrelados apenas ao aumento da força e hipertrofia muscular, mas também à composição corporal e, consequentemente, na taxa metabólica de repouso (RMR). OBJETIVO: Avaliar a resposta da RMR após 16 semanas de TP em mulheres na pós-menopausa. MÉTODOS: Participaram 28 voluntárias, subdivididas em dois grupos: treinamento (GT n = 17) e controle (GC n = 11). O programa de TP foi realizado em três sessões semanais, em dias alternados e com duração de aproximadamente 60 min/sessão, por 16 semanas. A intensidade da carga foi determinada por meio de zona alvo de repetições máximas (RM), com reajuste semanal de carga. O consumo de oxigênio (<img src="/img/revistas/rbme/v17n5/img01.jpg">O2) e da produção de gás carbônico (<img src="/img/revistas/rbme/v17n5/img01.jpg">CO2), por meio de calorimetria indireta de circuito aberto, foi utilizado para cálculo da RMR segundo equação de Weir (1949). ANÁLISE ESTATÍSTICA: Foi utilizado pacote estatístico Bioestat na versão 5.0, com nível de significância de p < 0,05. RESULTADOS: Houve aumento significante dos valores de MM e força muscular, somente no GT. Não foram encontradas diferenças significantes para os valores da RMR após a intervenção para ambos os grupos. CONCLUSÃO: O programa de TP de 16 semanas foi eficiente para promover alterações na composição corporal e força muscular de mulheres na pós-menopausa; entretanto, não houve alteração da RMR após a intervenção.

Validity of resting energy expenditure predictive equations before and after an energy-restricted diet intervention in obese women

BACKGROUND

We investigated the validity of REE predictive equations before and after 12-week energy-restricted diet intervention in Spanish obese (30 kg/m(2)>BMI<40 kg/m(2)) women.

METHODS

We measured REE (indirect calorimetry), body weight, height, and fat mass (FM) and fat free mass (FFM, dual X-ray absorptiometry) in 86 obese Caucasian premenopausal women aged 36.7±7.2 y, before and after (n = 78 women) the intervention. We investigated the accuracy of ten REE predictive equations using weight, height, age, FFM and FM.

RESULTS

At baseline, the most accurate equation was the Mifflin et al. (Am J Clin Nutr 1990; 51: 241-247) when using weight (bias:-0.2%, P = 0.982), 74% of accurate predictions. This level of accuracy was not reached after the diet intervention (24% accurate prediction). After the intervention, the lowest bias was found with the Owen et al. (Am J Clin Nutr 1986; 44: 1-19) equation when using weight (bias:-1.7%, P = 0.044), 81% accurate prediction, yet it provided 53% accurate predictions at baseline.

CONCLUSIONS

There is a wide variation in the accuracy of REE predictive equations before and after weight loss in non-morbid obese women. The results acquire especial relevance in the context of the challenging weight regain phenomenon for the overweight/obese population.

Acute sex hormone suppression reduces skeletal muscle sympathetic nerve activity

OBJECTIVES

Comparisons of sympathetic nervous system activity (SNA) between young and older women have produced equivocal results, in part due to inadequate control for potential differences in sex hormone concentrations, age, and body composition. The aim of the present study was to determine the effect of a short-term reduction in sex hormones on tonic skeletal muscle sympathetic nerve activity (MSNA), an indirect measure of whole body SNA, using an experimental model of sex hormone deficiency in young women. We also assessed the independent effects of estradiol and progesterone add-back therapy on MSNA.

METHODS

MSNA was measured in 9 women (30±2 years; mean±SE) on three separate occasions: during the mid-luteal menstrual cycle phase, on the fifth day of gonadotropin-releasing hormone antagonist (GnRHant) administration, and after 5 days add-back of either estradiol (n=4) or progesterone (n=3) during continued GnRHant administration.

RESULTS

In response to GnRHant, there were significant reductions in serum estradiol and progesterone (both p<0.01) and MSNA (25.0±1.9 vs. 19.2±2.4 bursts/min, p=0.04). Continued GnRHant plus add-back estradiol or progesterone resulted in a nonsignificant decrease (19.2±1.7 vs. 12.1±1.9 bursts/min, p=0.07) or increase (16.2±1.7 vs. 21.0±6.0 bursts/min, p=0.39), respectively, in MSNA when compared with GnRHant alone.

INTERPRETATION

The findings of this preliminary study suggest that short-term ovarian hormone suppression attenuates MSNA and that this may be related to the suppression of progesterone rather than estradiol.